1. Field of the Invention
This invention relates to a novel and continuous set of golf clubs set in accordance with the driving distance.
2. Related Art Statement
In `The Rules of Golf`, there is a requirement that the player shall start a stipulated round of golf with not more than fourteen clubs. The clubs are numbered, woods and irons each having their own consecutive number sequence. In this connection, professional and low handicap players generally use a set comprising a combination of 2 to 3 woods having a loft of not more than 23.degree., 10 to 11 irons having a loft of not less than 24.degree. and a putter. Average player frequently use a set comprising a combination of 4 to 5 woods, 7 to 9 irons and a putter. Among these clubs, the woods are used for shots requiring a long driving distance, and irons are used for shots requiring a direction stability. Further, it is desirable that the driving distance will be reduced in an orderly way from a wood driver toward a pitching wedge in the conventional golf club set.
The driving distance was actually measured with respect to each of 13 golf clubs being, for example, a combination of No. 1, No. 3, No. 4 and No. 5 woods, Nos. 3 to 9 irons, pitching wedge and sand wedge. As a result, the driving distance of the golfball gradually and smoothly reduces from the wood driver for professional players or the like capable of driving the golfball over a distance of not less than 200 m using the wood driver. For average players having a driving power of less than 200 m by the driver, however, a great stepwise difference in the driving distance between No. 5 wood and No. 3 iron exists. This is illustrated in a graph of FIG. 1. Therefore, a need exists to have the driving distance smoothly changed in accordance with the use of a number of golf clubs without causing the above stepwise difference even in their use by average players.
Further, it is known that an inertia moment Iy around a longitudinal axis passing through the center of gravity of the clubhead affects the size of a so-called "sweet area" in the clubhead for enhancing the directional stability of the golfball. In the conventional golf club set, the inertia moment on the y-axis is not considered to gradually increase in accordance with the reduction of the driving distance. This is shown by a curve A in FIG. 2 because the design concept of the wood is entirely different from that of the iron.